The point being the intermittent nature of the issue. I can get lucky and get 10 consecutive calls with no issue and other time I can make 10 calls that all have the issue. All calls made to the same source without hd audio involved. Therefore, in my opinion, suggesting that hd voice is the culprit is counterproductive. I think we need to move on and consider other possibilities.
I agree, based on my experience with my own iPhone 8 and on what you all guys are reporting, I think that the HD voice hypothesis has to be discarded.